Conventionally, various types of electronic devices have been developed and widely used. Among them, as a personal computer provided with an information calculation function (hereinafter, abbreviated as PC), a portable note PC and a stationary desktop PC are widely used. In the portable note PC, an image display unit having a display screen and a main unit are coupled by means of a hinge member that fastens them so as to be freely closed and opened. The main unit incorporates such as a circuit board on which a central processing unit (CPU) for executing a program and an electronic circuit are mounted, and a hard disk in which information is stored. The main unit also serves as a keyboard with plural operational keys arranged on a top surface of the portable note PC. The stationary desktop PC includes a main unit incorporating a circuit board on which a CPU for executing a program and an electronic circuit are mounted, and a hard disk in which information is stored; an image display unit having a display screen for displaying an image; and a keyboard for key operation or the like, each as separate casings.
Herein, various peripheral devices may be connected to the PC. Incidentally, there is a proposition of a multistage mounting device in which a fixed shelf and a hanging shelf for mounting each component of a computer system formed of the desktop PC and the peripheral devices connected to the desktop PC in a multistage fashion are provided (refer to Japanese Laid-Open Patent Publication No. 07-307587, for example).